FPSF in zone 5 with expansive soil
Hello all,
I have a foundation question. I’m in Colorado Springs, zone 5. Doing a single family build “pretty good house”. We’ve seen some articles on frost protected shallow foundations as a good choice for minimizing concrete and being suitable for expansive soil, as well as for our goal of fully insulating our slab. We have expansive clay on our site, but a reasonable slope (20″ in the 40′ of the 20×40 bldg footprint) to shed water away with drain to daylight. Local engineers are wanting to do a large overdig to replace the expansive soil and deeper footers (40-48″), rather than FPSF. It feels somewhat a case of this is what they usually do and less that FPSF is or isn’t appropriate. Would appreciate some feedback. Thanks!
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Replies
Do you really want to bet half a million dollars that you are right and the engineers are wrong?
If you want to cut your carbon foot print I say, find another option or more stable ground.
Walta
I could choose to just accept common practice (like studs 16" oc, a gas furnace, that houses leak enough to have decent air quality) or I can seek more knowledge and make an informed decision. I choose the latter which is why I ask questions on a building science site.
Do what the engineers say; don't compromise on your foundation. The carbon footprint of concrete is massively overblown in the first place.